Drive axles are commonly used in motorized platforms of all types, including trucks, buses, and automobiles, as well as off-road machines utilized in construction, mining, and agricultural fields. Typically, drive axles employ beveled differential gear structures for splitting driveline torque between dual opposed final drive half shafts. Such splitting avoids undue stresses on drivetrain components, and avoids excessive skidding and wear of powered driving tires as a vehicle turns about a radius.
Drive axle systems are traditionally lubricated by so-called “splash and spray” oil; that is, oil contained within a nonrotating reservoir is picked up and sprayed about the interior of the housing by at least one rotating gear structure that interfaces with the reservoir. Of course, the lubrication is required to achieve satisfactory operation of the drive axles and to avoid premature failures of associated operating components due to oil starvation, as will be appreciated by those skilled in the art.
Although beneficial to meet requisite lubrication demands, one deleterious side effect of splash and spray oil is a loss of torque resulting from efficiency losses created by churning of the oil. Various structures and methods have been utilized to reduce the churning beyond amounts determined necessary to assure effective lubrication. Typical apparatus and techniques have involved uses of interior ducting, shrouds, and baffles to channel and/or redirect the oil to specific regions within the housing to reduce efficiency losses. Others have involved use of inserts strategically positioned to physically displace excess oil within the lubricant reservoir. Although some of these approaches have had modest successes, none have substantially reduced churning losses. To the extent that such losses translate directly into operational expense, i.e. fuel costs, significant motivation remains to further reduce churning losses.